Find the derivative of the following functions (it is to be understand that a,b,c,d,p,q,r and s are fixed non-zero constants and m and n are integers):
`(a)/(x^(4))-(b)/(x^(2))+cosx`

Explanation

Let `y==(a)/(x^(4))-(b)/(x^(2))+cos x`
`=a.x^(-4)-b.x^(-2)+cos x`
`rArr(dy)/(dx)=(d)/(dx)(ax^(4)-bx^(-2)++cos x)`
`=a(d)/(dx)x^(-4)-b(d)/(dx)x^(-2)+(d)/(dx)cos x`
`=a(-4)x^(-5)-b(-2)x^(-3)+(-sin x)`
`=(-(4a)/(x^(5))+(2b)/(x^(3))-sinx)`